By washing textile objects, one has traditionally had the possibility to choose to treat these in a detergent solution based on water, or to utilize a dry cleaning method, where water is replaced by trichlorethene or perchlorethene. By what is known as common wash, which can be used for most articles of clothing, garments are placed in a treatment drum of a washing machine to be cleaned in a detergent solution based on water. For garments not washed in water, the garments are instead placed in a dry-cleaning machine and are cleaned in a wash-solution based on solvents, usually containing perchlorethene. Those solutions based on solvents have, from an environmental standpoint, been found to be inappropriate, and hence one has tried to find replacement liquids, which from a washing viewpoint are equally good as wash-solutions based on solvents earlier used, but which at the same time do not demonstrate the drawbacks from an environmental viewpoint, which are inherent in the wash-solutions based on solvents.
Such a replacement liquid having suitable properties for cleaning of textiles is carbon dioxide in liquid or supercritical state. The patent specification U.S. Pat. No. 5,267,455 describes a system for chemically cleaning textiles using carbon dioxide in liquid or supercritical state. This system include a treatment chamber, a supply tank for liquid carbon dioxide and likewise a vaporization chamber for liquid carbon dioxide, which has been used in the process and shall after purification be brought back to the supply tank. The liquid carbon dioxide is pumped from the supply tank to the treatment chamber, and when the cleaning process has been completed, from the treatment chamber to the vaporization chamber. The vaporization of the liquid carbon dioxide takes place by heating, and the evaporated gas is conveyed through filters and a condensing apparatus back to the supply tank. The described process depicts how the chemical cleaning using liquid carbon dioxide should possibly come about, but is by no way optimized with respect to recovering from treatment and vaporization chambers liquid and gaseous carbon dioxide respectively. Because of the existing pressure conditions in the supply tank and in the vaporization chamber one cannot completely empty the vaporization chamber of gas, without specific measures. The solution will be to evacuate surplus gas to the ambient air, which entails that this gas must be replaced from a gas supplier, and that to a cost which is not negligible.
WO 99/13148 describes a device for cleaning garments in liquid carbon dioxide. Like the apparatus of U.S. Pat. No. 5,267,455, WO 99/13148 describes a device comprising a treatment chamber, a supply tank and a vaporization chamber, which are mutually connected to each other by way of suitable tubes and valve means. Further, the device comprises compressor means, which is used partly, most important, to completely empty the treatment chamber of carbon dioxide, partly to serve as driving means for carbon dioxide gas, which during one in treatment process included vaporization process from the vaporizer via condenser means shall be brought back to the supply tank. To evaporate liquid carbon dioxide in the vaporizer there are arranged particular heating means, and further, the condensing of carbon dioxide gas, which via the compressor means is directed to the condensation means, takes place without taking care of the energy thereby released.
Thus one object of the present invention is to improve the device for cleaning textiles mentioned as known, as far as possible all in the system circulating carbon dioxide being taken care of, and after cleansing being brought back to the supply tank. Another object is to take care of the energy released during the process, and utilize this in process steps, where otherwise energy provided from outside has to be utilized.